Andrahäckning hos kanadagås Branta canadensis?

Abstract

Canada Geese Branta canadensis do normally not produce more than one clutch per year. On the island of Nidingen off the west coast of Sweden a pair of Canada Geese successfully reared one early brood of young in the spring (2 and 8 young respectively in 2011 and 2012). Apparently the same pair in both years, approximately 35–40 days after hatching the first brood, laid a second batch of eggs in the same nest. In this paper, these events are described in detail and alternative explanations are discussed. No indications of adoption of young or change of partner in the couple could be identified; hence the hypothesis of a true second brood remains strong.